Run nginx as unprevileged user

Author: rcmadhankumar

src/bci_build/package/appcontainers.py

@@ -251,6 +251,7 @@ def _generate_prometheus_family_healthcheck(port: int) -> str:
     "LICENSE",
     "20-envsubst-on-templates.sh",
     "30-tune-worker-processes.sh",
+    "40-unprivileged-mode.sh",
     "index.html",
 ):
     _NGINX_FILES[filename] = (Path(__file__).parent / "nginx" / filename).read_bytes()
@@ -278,6 +279,8 @@ def _get_nginx_kwargs(os_version: OsVersion):
                 "nginx",
                 "findutils",
                 _envsubst_pkg_name(os_version),
+                "sed",
+                "grep",
             ]
         )
         + (["libcurl-mini4"] if os_version.is_sl16 else []),
@@ -293,13 +296,14 @@ def _get_nginx_kwargs(os_version: OsVersion):
         ),
         "custom_end": textwrap.dedent(f"""
             {DOCKERFILE_RUN} mkdir /docker-entrypoint.d
-            COPY [1-3]0-*.sh /docker-entrypoint.d/
+            COPY [1-4]0-*.sh /docker-entrypoint.d/
             COPY docker-entrypoint.sh /usr/local/bin
             COPY index.html /srv/www/htdocs/
             {DOCKERFILE_RUN} chmod +x /docker-entrypoint.d/*.sh /usr/local/bin/docker-entrypoint.sh
-            {DOCKERFILE_RUN} install -d -o nginx -g nginx -m 750 /var/log/nginx; \
-                ln -sf /dev/stdout /var/log/nginx/access.log; \
-                ln -sf /dev/stderr /var/log/nginx/error.log
+            {DOCKERFILE_RUN} set -euo pipefail; mkdir -p /var/cache/nginx /var/run/nginx /tmp/client_temp /tmp/proxy_temp /tmp/fastcgi_temp /tmp/uwsgi_temp /tmp/scgi_temp;\
+                ln -sf /dev/stdout /var/log/nginx/access.log;\
+                ln -sf /dev/stderr /var/log/nginx/error.log;\
+                chmod -R 777 /var/cache/nginx /etc/nginx /var/run/nginx /var/log/nginx /tmp/client_temp /tmp/proxy_temp /tmp/fastcgi_temp /tmp/uwsgi_temp /tmp/scgi_temp;
             STOPSIGNAL SIGQUIT"""),
     }
 

src/bci_build/package/nginx/40-unprivileged-mode.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+
+set -e
+
+CURRENT_UID=$(id -u)
+if [ "$CURRENT_UID" -gt "0" ]; then
+    echo "$0: Running as unprivileged user (UID: $CURRENT_UID). Configuring for unprivileged mode (Port 8080)."
+
+    CONF_FILES="/etc/nginx/conf.d/default.conf /etc/nginx/nginx.conf"
+
+    for FILE in $CONF_FILES; do
+        if [ -w "$FILE" ]; then
+            if grep -q "listen .*80;" "$FILE"; then
+                echo "Changing port 80 to 8080 in $FILE"
+                sed 's/listen\s*80;/listen 8080;/g' "$FILE" > /tmp/client_temp/nginx_swap.conf && \
+                cat /tmp/client_temp/nginx_swap.conf > "$FILE" && \
+                rm -f /tmp/client_temp/nginx_swap.conf
+            fi
+
+            if [ "$FILE" = "/etc/nginx/nginx.conf" ]; then
+                echo "Redirecting NGINX temp paths and setting PID to /tmp in $FILE"
+                sed -e '/^user/d' \
+                    -e 's,^#\?\s*pid\s\+.*;$,pid /var/run/nginx/nginx.pid;,' \
+                    -e '/http {/a \    client_body_temp_path /tmp/client_temp;\n    proxy_temp_path /tmp/proxy_temp;\n    fastcgi_temp_path /tmp/fastcgi_temp;\n    uwsgi_temp_path /tmp/uwsgi_temp;\n    scgi_temp_path /tmp/scgi_temp;' \
+                    "$FILE" > /tmp/client_temp/nginx_ultra.conf && \
+                cat /tmp/client_temp/nginx_ultra.conf > "$FILE" && \
+                rm -f /tmp/client_temp/nginx_ultra.conf
+                echo "$0: Removed 'user' directive and updated PID path."
+            fi
+        fi
+    done
+
+    echo "$0: Listening on port 8080."
+fi

src/bci_build/package/nginx/README.md.j2

@@ -41,6 +41,12 @@ The template above is then rendered to `/etc/nginx/conf.d/default.conf` as follo
 ```nginx
 listen  80;
 ```
+## Running nginx as a non-root user
+To run the image as a less privileged user using the `nginx` user, do the following:
+```ShellSession
+$ podman run -it --user nginx --rm -p 8080:8080 -v /path/to/html/:/srv/www/htdocs/:Z {{ image.pretty_reference }}
+```
+**Note:** When running as the `nginx` user the default port is 8080.
 
 ## Environment variables